Electrochemical Synthesis of Individual Core@Shell
and Hollow Ag/Ag<sub>2</sub>S Nanoparticles
Donald
A. Robinson
Henry S. White
10.1021/acs.nanolett.9b02144.s001
https://acs.figshare.com/articles/journal_contribution/Electrochemical_Synthesis_of_Individual_Core_Shell_and_Hollow_Ag_Ag_sub_2_sub_S_Nanoparticles/9118421
This
letter presents an electrochemical methodology for structure-tunable
synthesis, characterization, and kinetic monitoring of metal–semiconductor
phase transformations at individual Ag nanoparticles. In the presence
of HS<sup>–</sup> in aqueous solution, the stochastic collision
and adsorption of Ag nanoparticles at a Au microelectrode initiates
the partial anodic transformation of Ag to Ag<sub>2</sub>S at each
particle. A single continuous current transient is observed for each
Ag nanoparticle reacted. The characteristic shapes of the transients
are distinct from previously reported amperometric recordings of electrochemical
reactions involving single nanoparticles and are highly uniform at
a constant applied potential. The average maximum current increases
while the event duration decreases as a function of increasing potential.
Independent of applied potential, the electrochemical transformation
event abruptly stops after converting ∼80% of the Ag in the
nanoparticle to Ag<sub>2</sub>S, a self-terminating process that does
not occur for bulk Ag electrodes under similar conditions. The resulting
products are a mixture of core@shell Ag@Ag<sub>2</sub>S nanoparticles
with and without voids in the core, as characterized by transmission
electron microscopy (TEM) and energy-dispersive X-ray spectroscopy
(EDX). Both the frequency and size of voids increase at more positive
potentials. The average size of the core@shell nanoparticles determined
by coulometric analysis of the current transients agrees well with
TEM measurements.
2019-07-26 18:38:01
bulk Ag electrodes
energy-dispersive X-ray spectroscopy
Ag nanoparticles
electrochemical transformation event
HS
event duration decreases
TEM
transmission electron microscopy
EDX
Ag 2 S